Protection of liquid-insulated electric apparatus



' 1,642,403 P 1927- M. BUCHHOLZ PROTECTION OF LIQUID INSULATED ELECTRIC APPARATUS Fileq April 16. 1925 In en/ a r 1%91 Back/1a /z z am 50 and ascend. Instead of air or a as, a solid Patented Sept. 13, 1927.

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1,642,403 PATENT OFFICE.

max ruonnonz, or CASSEL, GERMANY.

PROTECTION OF LIQUID-INSULATED ELECTRIC APPARATUS.,

Application filed April 16, 1925, Serial No.

My invention has reference to a method and means for protecting electric apparatus Operating in an insulating liquid, such as oil transformers, oil switches, grounding 5 "throttling coils, resistances and the like, and

it is one of the important objects of my invention to provide a device of very slmple construction and great reliability, and adapted to operate before extensive in ur1e to the apparatus to be protected can occur by sparking, overloading or other disturbances.

My invention is particularly based on the fact that in the case of disturbances in the operation of the apparatus to be protected or in the case of sparkingor other irregularities of operation, or whenever such irregularities are imminent, a rise of temperature will occur which can be utilized for operating suitable protective means associated with the apparatus.

I may for instance utilize a supply of gas such as air, enclosed in a container of metal, glass or other suitable material mounted in the oil filled vessel in close vicinity to the a paratus to be protected, such gas being liberated and allowed to ascend in the insulating liquid whenever a predetermined temperature of the oil is exceeded, owing to an unnormal operation of the apparatus. The ascending air bubbles will then cause .a variation of the insulating capacity of the liquid between the terminals of a protective circuit, thereby eifecting'the switching out of the apparatus or some other protective operation. The tem erature at which the gas is set free shoul be so selected as to cause the safety device to be operated before the occurring of sparking. or of other disturbances. The gas container may be provided with one or a plurality of openings which are closed readily fusible metals, resins or the like.

b The gas container may be replaced by a hollow. wire or wires which may form part of the electric outfit of the apparatus to be protected. Upon the melting of the closure of the openings in the container, part of the ;air or other gas enclosed-therein under normal or increased pressure, being expanded by the heat of its surroundings, will escape substance or. a li uid of low boiling point may be storedin t e container and the gases fmentalities shown and described in the specification as embodiments of these principles or vapors set free from these substances at an elevated temperature will then act on the 23,676, and in Germany January 19, 1922:

abled to watch the temperature of the insulating liquid at these points. I may even dlspense'with a container and replace it by some substance capable ofremaining unchanged, while being submerged in the ina becoming volatilized or emitting gases or vapors at an elevated temperature,such sub stances being easier freely arranged in the oil or heated in the insulation of the wires.

A protective device embodying this invention is illustrated in the drawings annexed to this specification by way of. example in a purely diagrammatic manner in elevation.

In the drawings, a is a transformer casing, 6 is the transformer, c are the, .windings, d are the leading-in insulations for. the conductors, e is an oil switch with a releasing coil 7 comprised in the protective circuit, two terminals of which E are arranged in the casinga to form a spark gap above the gas container G mounted. between the windings c of the transformer and closed by a fusible plug H. The container G is filled with air which, on the fusing of the plug H, being expelled by the heat generated by an abnormal working of the apparatus, will rise in bubbles, ridgmg the spark gap F, whereby the protective circuit is set operating so as to open the oil switch 6 and cut out the transformer.

Besides the form of' construction herein shown and described, the invention is susc'eptible of a variety of'other modifications and forms of application of the principle of sulating' liquid under normal conditions, but

my invention all of which operate substantially in a similar manner. The means of connecting the contacting device with the releasing circuit and the switching means are open to changes and alterations without any being susceptible of modifications without deviating from the spirit of my invention as set forth in the claim. 7

In the claim the term gases is meant to 5 comprise also vapors and fumes.

I claim: A protective device for transformers or the like comprising a casing in which the transformer is disposed, a supply of insulat- 10 ing liquid surrounding the transformer, a gas chamber arranged in the insulating liquid between the transformer coils and having an opening closed by a displaceahle closure means, a spark gap arrangedabove said clo sure means and adjacent thereto, said closure means being displaceable under abnormal working conditions of the apparatus to release the gaseous content of the chamber, the gases on release being adapted to displace the liquid from the spark gap,

In testimony whereof ll afix my signature.

MAX BUCOLZ. 

